Cytogenetic studies and H.L.A. pattern in Greek patients with A,B-Lipoproteinemia

Abstract

A,â-lipoproteinemia is an extremely rare genetic disorder of lipoprotein metabolism, associated with various biochemical abnormalities combined with clinical malabsorption. The aim of this study was to provide information concerning the cytogenetic and HLA patterns of three patients with A,â-lipoproteinemia, as well as to see if there is any correlation between specific HLA type and clinical course of the disease.

The study included seven persons. There were 3 patients (a girl and two boys aged 32, 30 and 22 years respectively) and their 4 healthy, first-degree relatives (two parents, a brother and a sister). Cytogenetic studies were
performed on PHA stimulated peripheral blood cell cultures of the three patients. Forty metaphase cells were analyzed for each one of them. The HLA typing was carried-out using the standard NIH microlymphotoxicity assay in all seven members of the family. B-cells were separated by the use of immunumagnetic beads CD19 coated.

The karyotypic study resulted in normal picture. No sporadic chromosome abnormalities were observed except of a small fragment- like acentric structure seen in only one cell in the case of one male patient (brother). The HLA pattern in the two most severely affected patients was identical (A2, 24, B18 (Bw6) Cw15, w7. DR8, 11, DQ4, 7). However, the only detectable difference between severely ill patients and the other members of the family was homozygosity for the HLA-B18. The HLA pattern of the third patient was A2, A24/B35, B44/ Bw4, Bw6/Cw4, Cw7/DR11, DR14, DR52/DQ5, DQ18.

This patient had no alleles for HLA B18. It is concluded that the karyotype of patients with A,â-lipoproteinemia is normal. Despite the identical pattern seen in the two most severely affected patients, no association could be found between any particular HLA type and this rare genetic disorder.

Key words: Immunogenetics, A,â-lipoproteinemia, HLA, Karyotype, Genetic disorders